Traditionally, the window leaves of previously known wooden window structures have been made with a carrying or supporting casement which surrounds a glass irrespective of whether the window leaf has the form of a single glass or if it comprises one or more additional glasses arranged in inner casements connected to an outer casement. The function of the casement is to form the carrying framework of the window leaf and for this purpose the casement includes wooden portions located inside as well as outside the glass or the outer glass. The outwardly exposed portions of the outer casement will then always be exposed to climatological stresses in the form of alternate moisture loads, wind and direct insolation. During periods of varying temperature the outer glass pane, most often puttied, will be exposed to alternating cold and heat. The glass material has completely other physical shrinkage characteristics than the wood material of the casement, which leads to strong alternate stress loads on the putty joint between the glass pane and the casement. Cracks will arise relatively fast in the putty joint leading to moisture penetration in the woodwork of the casement with the ensuing rot damage, in particular in the bottom part of the casement, which has relatively unprotected cross-cut wood in the corner joints where the side pieces of the casement meet the bottom piece thereof. In order to counteract dilapidation of the window leaves, constantly recurring maintenance of painting, completion of putty and the like, is required.